Give three examples to illustrate that friction is a necessary evil.

Hint: Frictional force refers to the force generated by two surfaces that contact and slide against each other.
Friction generates heat because it causes the molecules on rubbing surfaces to move faster and have more energy.

Complete step-by-step solution:
A few factors affecting the frictional force:
These forces are mainly suffering from the surface texture and amount of force impelling them together.
The angle and position of the body affect the quantity of frictional force.
If an object is placed flat against an object, then the frictional force is going to be adequate to the load of the body.
If an object is pushed against the surface, then the frictional force is going to be increased and becomes quite the load of the body.
The frictional force causes tons of losses generally upkeep and wear and tear of machinery. Hence it's considered evil. But most crucial tasks can't be administered without the presence of friction. Hence it's considered as a necessary evil.
The examples for instance that friction may be a necessary evil are:
1. If friction was absent, we might not be ready to walk.
2. Friction is important to burn a matchstick.
3. It is due to friction that we will write on a board with chalk.

Note:There are two methods of accelerating friction: one is by making the surfaces rough and therefore the other by increasing the mass of the body that's moving. Rougher surfaces have more friction between them than smoother surfaces. That's why we put sand on icy sidewalks and roads.